I'm a new DSLR owner. I'm shooting both in raw and jpg and use Aperture for photo editing. My question is, for best printing results when I send to photo lab, what's the best format to send in? Is it tiff, png, bmp or another format?

Also can anyone suggest a photo lab to use? I have no knowledge of photo labs are the mass merchandisers i.e. Walmart, Walgreen or CVS good choices or am I better off using a company like York Photo labs?